This invention relates to a high speed, photographic quality printer. More particularly, the invention relates to a method of separating a sheet of print media from a stack of sheets, the sheets being porous.
The applicant has developed various printheads which provide high speed, photographic quality printing. The printheads comprise ink jet nozzles arranged in an array. The ink jet nozzles are formed using microelectromechanical systems (MEMS) technology. The use of MEMS technology results in very high speed printing capabilities where pages can be printed at a rate of up to two pages per second (for double-sided printing).
To facilitate such high speed printing, it is important, firstly, that the paper fed to the printing station of the printer is accurately aligned and capable of the required feed rate with as little likelihood as possible of paper jams or the like, occurring. Secondly, the paper must be able to be fed to the printing station at a rate sufficient to use the high speed printing capabilities of the printing station to its fullest extent.
According to the invention, there is provided a method of separating a sheet of print media from a stack of sheets, the sheets being porous and the method including the steps of:
blowing fluid on to a top surface of a topmost sheet of the print media on the stack so that the fluid passes through at least the topmost sheet of the stack; and
capturing at least a part of the topmost sheet for conveyance to a printing station of a printer.
The method may include blowing the fluid on to the top surface of the topmost sheet through an aperture means of a pick up means of a print media feed arrangement. The pick up means may be in the form of a pick up bar. The aperture means of the pick up bar may be in any of a number of different forms. For example, the aperture means may be in the form of a channel extending longitudinally along the bar. Instead, the bar may support a plurality of longitudinally spaced, discrete orifices, the orifices defining the aperture means.
The method may include, initially, prior to capturing said at least part of the topmost sheet, lifting said at least part of the topmost sheet from the stack. The method may include causing said lifting of said at least a part of the topmost sheet by creating a low pressure region between a face of the pick up means and the top surface of the topmost sheet of print media.
Preferably, the method includes maintaining the pick up means in spaced relationship relative to the top surface of the topmost sheet of print media to cause said low pressure region.
The method may include capturing said at least part of the topmost sheet of print media by the pick up means, preferably by reversing a direction of fluid flow through the pick up means to cause a change from a blowing action to a suction action.
The method may include conveying said topmost sheet of print media in a direction substantially normal to a direction of flow of fluid blown on to the stack.